Spark gap switches for oversized waveguide



Jan. 28, 1969 J. P.- QUINE ET AL 3,424,943

SPARK GAP SWITCHES FOR OVERSIZED WAVEGUIDE Filed March 6, 1967 INVENTORJ. J'd/IN 1P Qwm: m

BY gi 0 0 Y United States Patent 3,424,943 SPARK GAP SWITCHES FOR OVERSIZED WAVEGUIDE John P. Quine, Schenectady, and Cousby Younger, Scotia, N.Y., assignors to the United States of America as represented by the Secretary of the Air Force Filed Mar. 6, 1967, Ser. No. 621,410 US. Cl. 315-39 Int. Cl. H01p 1/14 6 Claims ABSTRACT OF THE DISCLOSURE This invention relates generally to spark gap switches, and more particularly to spark gap switches for oversize rectangular waveguides.

High pressure spark gap switches have been utilized in the past in standard size waveguides. There has, however, never been found a switch of this nature which would operate properly in an oversize waveguide at atmospheric pressure.

A spark gap switch in an oversized waveguide having cross sectional dimensions on the order of two wave lengths should be capable of operating at power levels eight to ten times greater than the power levels for the standard waveguide switches. Difficulties to be overcome because of this include the obtaining of simultaneous firing of all the spark gaps and the suppression of spurious mode generation. Unless all spark gaps are fired simultaneously, conversion of energy to spurious modes and pulse-to-pulse time and waveform jitter can occur.

Spark gap switches of various types have been tried but have proved unsatisfactory. One such switch consists of a two column configuration utilizing two trigger spheres, one ground sphere and two ground hemispheres in each column. This configuration was unable to provide the spurious mode conversion and low dissipation losses at acceptable levels.

The present invention has for an object to provide a new and improved microwave switch.

It is another object of this invention to provide a new and improved spark gap switch for an oversized waveguide.

It is a further object of this invention to provide a new and improved microwave spark gap switch for use at atmospheric pressure.

It is still another object of this invention to provide a new and improved fast ultra high power microwave switch.

It is still a further object of this invention to provide a new and improved spark gap switch which is capable of operating at power levels eight to ten times greater than the power levels for other waveguide switches.

These and other advantages, features and objects of Patented Jan. 28, 1969 ice the invention will become more apparent from the following description taken in connection with the illustrative embodiment in the accompanying drawing wherein:

The figure is front perspective view partly in section of a spark gap switch made in accordance with the principles of this invention.

Referring now in more detail to the aforesaid illustrative embodiment of our invention, and with particular reference to the drawing illustrating the same, the numeral 10 generally illustrates the waveguide'cavity with an eight trigger switch in a two column configuration. Trigger spheres 12 enter the waveguide wall through a Teflon insulator 14. The trigger line is provided with three RF chokes of brass spacers 16 and Teflon washers 18 to prevent microwave leakage of any residual spurious modes that might couple to the coaxial trigger lines.

The elongated ground spheres 20 which may be brass or other similar material are mounted alternately between the trigger spheres with a half elongated sphere located on the waveguide at each end of the two columns. At the Waveguide center is located a polystyrene post 22 which minimizes possible coupling to the TEg mode.

The two columns of ground spheres and trigger spheres may be disposed symmetrically about the center of the waveguide and spaced apart by one third the width of the waveguide. This is done to minimize the T'E mode coupling on a gross basis; the dielectric post is then employed to reduce the TE mode coupling to very low values.

With this invention it is possible for the first time to obtain a change in phase of the reflection coefficient in excess of 180. This invention has produced a maximum phase shift of 230; devices of this nature hitherto known could produce a phase shift of only about far below that needed for switching. In addition this switch will operate effectively at. a microwave power level in the order of 1.4 megawatts. Similarly, the spark gap switch of this invention will operate in a time period not exceeding a few nano-seconds depending upon the power level and size of the waveguide utilized.

Although the invention has been described with reference to a particular embodiment, it will be understood to those skilled in the art that the invention is capable of a variety of alternative embodiments within the spirit and scope of the appended claims.

We claim:

1. A spark gap switch for low pressure oversized waveguides comprising: an oversize rectangular waveguide section; a plurality of trigger spheres, mounted on a support rod means through the wall of said waveguide and in insulated relationship therewith; a radio frequency choke mounted in said wall surrounding said support rod and insulating means; and a plurality of elongated ground spheres mounted on support rods alternately between said trigger spheres, said support rods fixed to the wall of the waveguide.

2. A spark gap switch according to claim 1 wherein: there are eight trigger spheres in two columns parallel to the walls of the waveguide, said spheres spaced apart less than half the wavelength of the wave energy to be switched.

3. A spark gap switch according to claim 2 wherein: there are ten elongated ground spheres and portions thereof mounted in two columns parallel to the walls of the waveguide.

3 4 4. A spark gap switch according to claim 3 including: References Cited a post means mounted between said columns and parallel UNITED STATES PATENTS thereto for the prevention of intermodal coupling.

5. A spark gap switch according to claim 2 wherein: 3,351,806 11/1967 Father 315-39 said columns of ground spheres and trigger spheres are 5 disposed symmetrically about the center of the waveguide ELI LIEBERMAN Primary Exammer' and are spaced apart by one third the width of the wave L. ALLAHUT Assistant Examiner. guide.

6. A spark gap switch according to claim 1 wherein: US. Cl. X.R. the radio frequency choke comprlses brass spacers and m 313 196, 197; 333 98, 13; Teflon washers. 

